Jack Eden, an authoritative local voice on gardening for several decades who dispensed advice over the radio and in a Washington Post column and became a horticultural lightning rod for his advocacy of pesticides, died Jan. 17 at a hospice in Williamsburg. He had colon cancer and died on his 79th birthday.

For many years, the self-taught green thumb was a dominant figure in gardening advice. As the longtime host of "Over the Garden Fence" on WTOP-AM and in his freelance gardening column, "Garden of Eden," in The Post's Real Estate section, Mr. Eden offered counsel to homeowners, much of it revolving around the use of pesticides and synthetic fertilizers.

His advocacy of chemical gardening became an anachronism for many younger professional and amateur gardeners who did not share his enthusiasm for insecticides such as Malathion and Diazinon.

Responding to reader complaints, Post ombudsman Richard Harwood called Mr. Eden "a chemical enthusiast and promoter of pesticides and herbicides that pollute ground water and wind up in the Chesapeake Bay."

In an interview, Holly Shimizu, executive director of the U.S. Botanic Garden in Washington, said Mr. Eden developed a large following because he offered seemingly easy solutions to obtaining the "perfect lawn."

Yet his reliance on pesticides, some of which he appeared to endorse commercially, placed him squarely in an "an older generation who grew up with chemicals being the answer," Shimizu said.

John Francis Eden was born Jan. 17, 1930, in Brooklyn, N.Y. He received a bachelor's degree in English from Seton Hall University in South Orange, N.J., in the mid-1950s. During the Korean War, he served in the Army and was a journalist for the military newspaper Stars and Stripes.

While he was doing public relations work in New York, he and his wife bought their first home, on a one-acre plot of land about 60 miles north of the city. To save money, he once said, he decided to take the landscaping into his own hands. From there, his interest sprouted into a gardening show on a radio station in Mount Kisco, N.Y.

He settled in the Washington area in the early 1970s to take an editing job at the Consumer Product Safety Commission. He began gardening spots on WAVA-FM before moving to WTOP about four years later.

His affiliation with WTOP lasted about 20 years, during which time he also wrote about gardening for the Washington Star, the Washington Times and then The Post. His "Garden of Eden" column ended abruptly in 1996 over a payment dispute involving the Internet use of his column.

He subsequently launched his own Web site, http://www.jackeden.com, which he wrote for until the end of 2007. Over the years, Mr. Eden's radio reports aired in other cities, including Chicago, Detroit and Philadelphia. He also taught continuing-education seminars on horticulture as part of the Christopher Wren Association at the College of William and Mary in Williamsburg.

Mr. Eden, a Potomac resident, tended his own 5,000-square-foot front lawn as well as flower, herb and evergreen gardens. He did all the gardening himself, he told the Washington Times, adding, "Who else could I trust?"

Survivors include his wife of 53 years, Patricia Wohlever Eden of Potomac, and two children, Jill Eden Burns of Phoenix and Scott Eden of Williamsburg.